Air-cooled transformer



Oct. 6, 1953 E. D. TREANOR AIR-COOLED TRANSFORMER Filed Oct. 12, 1949Inventor-z Edward D.Tr-e an or, by

His Attorney.

Patented Oct. 6, 1953 AIR-COOLED TRAN SFORMEB Edward D. Trcano'r,Pittsfield, Mass., assignor to General Electric Company, a corporationof New York Application October 12, 1949, Serial No. 121,013 1 Claim.(Cl. 257 191) This invention relates to stationary electrical inductionapparatus, and more particularly to a cooling device for such apparatus.

In. the construction of all but the smaller size transformers, it isuniversal practice to provide some type of cooling system for thetransformer in order to conduct away the heat generated by theelectrical losses of the transformer.

It is an object of my invention to provide a simple and economicalarrangement for air cooling stationary electrical induction apparatus,such as transformers.

It is a further object of my invention to provide a new and improvedarrangement for providing forced circulation of air internally andexternally of a transformer structure.

In accordance with these objectives, my invention provides a new andimproved cooling structure for a transformer in which an electric motordrives two sets of fan blades, one set of blades providing for theinternal circulation of air within the transformer, while the other setof fan blades provides the external circulation of air about thetransformer structure.

The features of my invention which I believe to be novel are set forthwith particularity in the appended claim. My invention itself, however.both as to its organization and use, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawing in whichthe single figure represents a front elevation, partially cut away, of atransformer equipped with the forced air cooling means .Of my invention.

Referring now to the drawing, there is shown a transformer tank 1containing a magnetic core I having. winding. legs 3 and 4 which areconnected atxthe top and bottom, respectively, by yoke members 5 and 6.Each of the leg membets 3 and .4 is provided with an electrical windingwhich may consist of a plurality of concerntrio cylindrically-woundcoils l, :8, and 9 such as are: illustrated in a partially cutaway viewon winding leg .3, These coils maybe connected tother in any desiredmanner to achieve whatever electrical characteristics are desired. Theparticular electrical relation existing between the various coils-isnotpertinent to my invention. Cylindricallv-wound coils 1,8, and 9 areseparated from each other by suitable axial spacers- (notshown) so as tomaintain axial ducts in for a purpose to be hereinafter described. Thecoils :8 and s on each winding leg are surrounded on their outerperiphery by a cylinder H of insulating material.

Conccntrically mounted about the core and winding assembly is adouble-walled bafile ii. The outer wall 13 of the baffle is mounted inspaced relation to the wall of the transformer tank I by any suitablemeans, such as brackets, while the inner wall 14 ofthe baflle is mountedin spaced relation to the surface of insulating cylinders i I, andconforms in shape generally to the outer contours of insulatingcylinders H. Thus an air duct is provided between the outer wall 13 ofthe braille and the inside surface of the transformer tank, and alsobetween the inner wall H of the baifie and the outer surface ofinsulating cylinders H.

A metal hood I5 surrounds the top of the transformer tank and extendsdownwardly for the greater part of the height of the transformer tankstructure. The hood I5 is spaced away from the exterior of thetransformer tank structure to provide a chamber through which air maycirculate.

In order to provide both internal and external air circulation inaccordance with my invention, there is vertically mounted on top of thehood l'5 an electric motor is having rig-idly attached to its shaft twosets of fan blades I1 and I8, respectively.

As will be seen from the drawing, fan blades H are contained within thechamber formed between the exterior of the tank I and the hood l5,whereas fan blades it are contained within the chamber formed by theinside surface of the tank casing and the outside wall I; of baille II.

It is preferable that the direction of air flow on the outside andinside surfaces of the transformer casing should be in oppositedirections in order to provide counter-flow cooling; that is, thedirection of air flow in the chamber formed between hood l5 and. theouter surface of tank I should be opposite to the direction of air flowin the chamber formed between the inner surface of tankl and the outerwall 13 of baffle 12. This is shown by the air direction 'fi'ow arrowsin the drawing.

Fan blades l1 cause air to be drawn in from the atmosphere and to beforce-circulated th o gh e chamber formed between hood l5 and theexterior surface of transformer tank 1. Wh le circula mg hr ugh hischamber, the air passes ver cooling tubes 1-8 through which the nternalair .of the transformer t nk circula es. as will be hereinafterexplained. The circulation of the ext rnal .air around the coolin ube l9and around the exterior surface of tank 1| conducts away heat from thetransformer tank, and also from the cooling tubes l9.

Fan blades l8, which are mounted on the same shaft as fan blades ll,cause a circulation of the internal air of the transformer tank partlythrough the cooling tubes [9 and partly in proximity to the walls of thetransformer tank. As will be noted from an inspection of the air flowdirection arrows, fan blades [8 cause air from inside the transformertank to pass partly through the external cooling tubes I9 and partlythrough the chamber formed between the inside surface of the tank I andthe outer wall [3 of baffle l2. This arrangement insures that all air inthe transformer tank is either circulated through the cooling tubes [9which have large heat-dissipation areas, or in close proximity to thewalls of the tank which also have large heatdissipation areas. The airafter having passed through the cooling tubes I9 or through the chamberbetween the inner surface of tank I and the outer wall E3 of bailie I2then passes upwardly through the ducts H3 between the cylindricalwindings l, 8 and 9, and also through the duct formed between theexterior surface of insulating cylinder H and the interior wall Id ofthe baflie I2. The air which passes into the duct between the insulatingcylinders I l and the inside wall I l of the bafile l2 passes outthrough slots 28 in insulating cylinders II and thence through the ductformed between cylindrical coil windings 1 and 8 into the upper part ofthe transformer tank and back through the fan blades Hi again. It can beseen that ducts Ill and the duct between the exterior of insulatingcylinders II and the radially inner surface of wall i l of the bafile l2are in parallel with each other with respect to the flow of air or othergaseous cooling fiuid through the encasing means or tank I. However, theducts just mentioned are in series fluid fiow relationship with respectto the duct or chamber formed between the outer wall l3 of the baffleand the inner wall surface of the tank or encasing means I.

Since an air-cooled transformer tank of this type is ordinarily operatedat atmospheric pressure, a certain amount of interchange of air occursbetween the air of the atmosphere and that inside the tank in order tomaintain pressure equilibrium. This interchange for pressureequalization may occur where the fan shaft enters the transformercasing, if a relatively loose seal is used at this point. Alternatively,if, a'tight seal is employed at the point where the fan shaft enters thetransformer casing, it obvious that breather means such as are wellknown in the art could be mounted on the transformer casing to providefor pressure equalization between the interior of the tank and theatmosphere.

In this connection, the internal fan 18 serves the additional purpose ofpreventing the deposition of dust from the atmosphere on the windings l,8, 9 of the transformer, thereby aiding in the quicker dissipation ofheat from the windings.

Thus, it can be seen that the dual fan system of my invention provides afan element for circulating air inside of the transformer tank and outthrough cooling tubes which surround the tank, and another fan elementwhich provides for an external circulation of air around the externalsurface of the tank and around the external surface of the cooling tubesthrough which the internal air passes. Through the cooperation of thesetwo fan elements an internal and an external circulation of air isprovided, with both fan elements being driven by one motor.

While there has been shown and described particular embodiments of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications can be made therein without departing from theinvention and, therefore, it is aimed in the appended claim to cover allsuch changes and modifications as fall within the true spirit and scopeof the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

A cooling means for an apparatus contained within an encasing meanscomprising a motor mounted adjacent said encasing means, a shaft turnedby said motor, two sets of fan blades displaced axially from one anotheron said shaft, a hood enclosing said encasing means but spaced therefromto form a shallow chamber about said encasing means, said hood havingopenings for the entrance and exit of atmospheric air, one of said setsof fan blades being positioned within said chamber to circulate air insaid chamber, said second set of fan blades being positioned interiorlyof said encasing means to circulate a gaseous cooling fluid within saidencasing means, a double-walled baffle positioned between the interiorwall surface of said encasing means and the exterior surface of saidapparatus, said baiile having a radially outer axially-extending wallconforming substantially to the shape of the axially-extending innerwall surface of said encasing means and extending for a substantial partof the length thereof but being displaced from said axially-extendinginner wall surface sufficiently to provide a shallow first duct for thepassage of said gaseous cooling fluid, said baffle having a radiallyinner wall substantially conforming in shape to the portion of the outersurface of said apparatus which extends axially of said encasing meansbut displaced from said outer surface of said apparatus sufiiciently toprovide a shallow second duct for the passage of said gaseous coolingfluid between the radially inner surface of said inner wall of saidbafile and said outer surface of said apparatus, said baffle having afirst radially extending wall portion adjacent but displaced from an endof said encasing means, said first radially extending wall portionjoining together said radially inner and outer axially-ex tending wallsof said bafiie to restrain passage of cooling fluid between said innerand outer Walls of said bafiie, the spaced arrangement of said firstradially extending wall portion from the adjacent end of said encasingmeans permitting fluid flow between said first and second ducts at saidend of said encasing means, said baflie having a second radiallyextending wall portion axially displaced beyond the end of saidapparatus and adjacent but displaced from an opposite end of saidencasing means, said second radially extending wall portion beingattached to said radially outer wall of said baffle and enclosing thearea defined by said outer wall, said second set of fan blade beingpositioned between the axially outer surface of said second radiallyextending wall portion and the end wall of said encasing means, saidsecond radially extending wall portion being apertured adjacent saidsecond set of fan blades to permit passage of said gaseous cooling fiuidto said second set of fan blades from said second duct, said second setof fan blades providing a circulation of said gaseous cooling fluid in aseries path comprising said first and second ducts, and axiallyextending radiating tubes within said chamber, one end of said radiatingtubes connected to said encasing means axially between said secondradially extending wall portion and the adjacent end of said encasingmeans, and the other end of said tubes connected to said encasing meansaxially between said first radially extending wall portion and theadjacent end of said encasing means, said second set of fan bladesproviding circulation of said gaseous cooling fluid through said tubes.

EDWARD D. TREANOR.

6 References Cited in the file of this patent UNITED STATES PATENTSNumber Number Name Date Randall Jan. 13, 1914 Demers Oct. 13, 1931Burnham May 2, 1944 Blancha Nov 7, 1944 Melville July 20, 1948 FOREIGNPATENTS Country Date Great Britain Dec. 11, 1930 Great Britain July 18,1938 Switzerland Sept. 16, 1947

